How does the temperature of soybean oil affect the viscosity of the oil? In this lesson, students will determine the viscosity of soybean oil (vegetable oil) at different temperatures. They will use thermometers and the viscosity chart.
Students study the physical properties of different fluids and investigate the relationship between the viscosities of liquid and how fast they flow through a confined area. Student groups conduct a brief experiment in which they quantify the flow rate to understand how it relates to a fluid's viscosity and ultimately chemical composition. They explore these properties in milk and cream, which are common fluids whose properties (and even taste!) differ based on fat content. They examine control samples and unknown samples, which they must identify based on how fast they flow. To identify the unknowns requires an understanding of the concept of viscosity. For example, heavy cream flows at a slower rate than skim milk. Ultimately, students gain an understanding of the concept of viscosity and its effect on flow rate.
Students are introduced to the similarities and differences in the behaviors of elastic solids and viscous fluids. Several types of fluid behaviors are described Bingham plastic, Newtonian, shear thinning and shear thickening along with their respective shear stress vs. rate of shearing strain diagrams. In addition, fluid material properties such as viscosity are introduced, along with the methods that engineers use to determine those physical properties.
Students learn about the underlying factors that can contribute to Plinian eruptions (which eject large amounts of pumice, gas and volcanic ash, and can result in significant death and destruction in the surrounding environment), versus more gentle, effusive eruptions. Students explore two concepts related to the explosiveness of volcanic eruptions, viscosity and the rate of degassing, by modelling the concepts with the use of simple materials. They experiment with three fluids of varying viscosities, and explore the concept of degassing as it relates to eruptions through experimentation with carbonated beverage cans. Finally, students reflect on how the scientific concepts covered in the activity connect to useful engineering applications, such as community evacuation planning and implementation, and mapping of safe living zones near volcanoes. A PowerPoint® presentation and student worksheet are provided.